In engineering, there is often the situation of supplying a plurality of loads with electrical energy using adapted control electronics. In this case, lighting devices, in particular with LEDs (LED—light-emitting diode), are increasingly important, for example; lights of motor vehicles, in particular, are being implemented more and more frequently using LEDs, and in vehicle construction, in particular, there is then the problem that a plurality of different lights must be operated with different electrical characteristic variables, that is to say voltage or current, using the control electronics, in which case a further difficulty is that the voltage supply (on-board voltage) is generally not particularly stable. In addition, it should be borne in mind that different light functions are provided in a very tight space beside one another, for example in a vehicle headlight or in a tail light. It would therefore be desirable, also for reasons of space, for an individual space-saving electronic system to be sufficient.
As far as the implementation of lighting systems with LED lights is concerned, the voltage to be applied to an LED light is known to result from the current to be set; in addition to the brightness, the current also determines the light color; it goes without saying that the voltage also depends on whether there is one LED or whether a plurality of LEDs are connected in series. U1timately, the voltage here is therefore only the result of variables to be set.
It is conventional in practice to use a separate converter circuit for each light function, which circuit generates a stable current for the LEDs from the unstable supply network. However, this is complicated and expensive, and a relatively large amount of space is moreover also required, apart from the relatively high losses in such electronics. In this context, it is also already occasionally common practice to use a voltage converter to generate a central stable voltage from which the corresponding current is then generated for a plurality of LED lights. Only one conversion stage is provided here for a plurality of outputs, in which stage the current is then divided among a plurality of channels; control using a time offset is provided for this purpose, with the result that only one light can ever be switched on for a short period of time (in the microseconds range) or else considerable losses occur in the circuit. This known principle can be used only for low currents where the losses are small on account of the low current intensity.